WEBVTT 1 00:00:00.160 --> 00:00:04.080 Welcome to the deep dive. Today, we're plunging quite literally 2 00:00:04.200 --> 00:00:06.639 deep underground into the world of. 3 00:00:06.559 --> 00:00:08.480 Mining, a really challenging environment. 4 00:00:08.640 --> 00:00:12.839 Absolutely, we're going to explore the pretty amazing technologies that 5 00:00:12.919 --> 00:00:17.000 let people communicate, track where they are, and most importantly, 6 00:00:17.079 --> 00:00:20.559 stay safe when there are hundreds, maybe thousands of feet down. 7 00:00:20.679 --> 00:00:23.000 It's a world away from our usual signal bars, isn't it? 8 00:00:23.239 --> 00:00:25.800 Totally? And our insights today they're pulled from a really 9 00:00:25.839 --> 00:00:30.640 detailed technical document all about wireless comms and RFID sensor networks, 10 00:00:30.920 --> 00:00:32.679 specifically in underground minds. 11 00:00:32.799 --> 00:00:36.759 So we're talking cutting edge stuff built for extreme conditions exactly. 12 00:00:36.799 --> 00:00:40.039 You'll hear about some surprising breakthroughs like how radio waves 13 00:00:40.079 --> 00:00:45.000 can actually travel through solid rock, ingenious tracking systems, and 14 00:00:45.079 --> 00:00:47.520 the superstrict safety measures that underpin everything. 15 00:00:47.560 --> 00:00:50.320 Okay, let's get into it fundamentally. Why is it so hard? 16 00:00:50.359 --> 00:00:54.479 Why do our normal phones, our radios just stop working 17 00:00:54.560 --> 00:00:54.960 down there? 18 00:00:55.039 --> 00:00:58.399 Well, the biggest culprit is signal attenuation. Think of the 19 00:00:58.479 --> 00:01:00.840 rock itself. It just soaks up like. 20 00:01:00.759 --> 00:01:02.960 A giant sponge for radio waves. 21 00:01:02.840 --> 00:01:07.159 Pretty much, the signal strength just plummets, and it's not 22 00:01:07.280 --> 00:01:11.079 just getting weaker. The rock absorbs it scatters, it even 23 00:01:11.159 --> 00:01:13.239 bends it. It really messes with the signal. 24 00:01:13.319 --> 00:01:16.319 Okay, so the Earth itself is the barrier, right, and. 25 00:01:16.280 --> 00:01:20.239 Then you've got electromagnetic interference EMI from all the heavy machinery, 26 00:01:20.280 --> 00:01:21.040 the power systems. 27 00:01:21.120 --> 00:01:23.799 Ah, so it's noisy electrically too exactly. 28 00:01:23.799 --> 00:01:27.359 It just adds another layer of difficulty for any kind 29 00:01:27.359 --> 00:01:29.120 of wireless signal trying to get through. 30 00:01:29.560 --> 00:01:32.959 So if modern wireless struggled, what did they do historically? 31 00:01:33.599 --> 00:01:36.599 Before all this fancy tech I imagine wires were involved. 32 00:01:36.640 --> 00:01:39.480 Oh, definitely, wired solutions were the only game in town. 33 00:01:39.560 --> 00:01:43.519 For a long time. You had simple magnetotype phones basically 34 00:01:43.599 --> 00:01:46.439 like a basic intercom for really short distances. 35 00:01:46.040 --> 00:01:47.239 Point to point, very limited. 36 00:01:47.319 --> 00:01:49.799 Yeah. Then you had paging phones. Those are quite common 37 00:01:49.840 --> 00:01:53.680 actually simple to install. Used a two wire party line system. 38 00:01:53.519 --> 00:01:55.560 Party line so only one person talks at a. 39 00:01:55.519 --> 00:01:57.680 Time exactly, and they had their own battery, which is good, 40 00:01:57.719 --> 00:02:01.000 made themselves contained, but yeah, limited conversation. 41 00:02:00.640 --> 00:02:03.159 Okay, still pretty basic. Did they ever try to use 42 00:02:03.200 --> 00:02:06.120 the wiring that was already there, like power lines? 43 00:02:06.439 --> 00:02:09.240 They did? That was the next step. Carrier current systems 44 00:02:09.759 --> 00:02:14.199 quite clever really, They used existing mind wiring AC or 45 00:02:14.360 --> 00:02:18.439 DC power lines sometimes even the big hoystropes, the hoist ropes. 46 00:02:18.599 --> 00:02:18.840 Wow. 47 00:02:18.919 --> 00:02:21.479 Yeah, they basically turned all that metal into a kind 48 00:02:21.479 --> 00:02:25.680 of distributed antenna for radio frequency signals. It worked best 49 00:02:25.719 --> 00:02:27.000 with low and medium frequencies. 50 00:02:27.120 --> 00:02:29.400 Makes sense, lower frequencies penetrate better. 51 00:02:29.479 --> 00:02:33.840 Right, And you saw these as trolley carrier phones running 52 00:02:33.840 --> 00:02:37.199 on the trolley lines or hoist rope radios using those 53 00:02:37.240 --> 00:02:38.039 main shaft ropes. 54 00:02:38.159 --> 00:02:41.840 That's resourceful using the infrastructure. But I'm guessing wires, even 55 00:02:41.919 --> 00:02:44.400 use cleverly have big downsides underground. 56 00:02:44.520 --> 00:02:49.680 Huge downsides demand one vulnerability a rock fall, a machine accident, 57 00:02:50.360 --> 00:02:53.120 cut that cable and your communication is gone instantly. 58 00:02:53.159 --> 00:02:54.960 Well redundancy there not really. 59 00:02:55.120 --> 00:02:57.960 And the other big issue was mobility. Miners were essentially 60 00:02:58.000 --> 00:03:00.360 tethered to wherever a phone point was installed. 61 00:03:00.319 --> 00:03:03.879 Which is terrible in a dynamic, potentially dangerous place like 62 00:03:03.919 --> 00:03:05.159 a mine, you need. 63 00:03:05.039 --> 00:03:07.800 To move exactly. So it really highlighted the need for 64 00:03:07.840 --> 00:03:10.199 something truly wireless, something more robust. 65 00:03:10.400 --> 00:03:13.759 Okay, So that leads us to the big question, can 66 00:03:13.800 --> 00:03:17.400 you actually punch a signal through the rock? Forget wires 67 00:03:17.479 --> 00:03:19.520 just straight through the earth? Is that where through the 68 00:03:19.560 --> 00:03:21.120 earth or TTD comes in. 69 00:03:21.319 --> 00:03:25.599 That's precisely. It TTE communication was the breakthrough. These systems 70 00:03:25.759 --> 00:03:30.919 use very low frequency electromagnetic waves. We're talking frequencies specifically 71 00:03:31.000 --> 00:03:35.439 chosen because they can penetrate hundreds of meters of solid rock. 72 00:03:35.879 --> 00:03:39.280 Hundreds of meters. That's significant. But low frequencies usually mean 73 00:03:39.400 --> 00:03:41.840 low bandwidth, Right, how do you get voice through? 74 00:03:41.960 --> 00:03:45.840 Good point? That's where digital signal processors DSPs come in. 75 00:03:46.199 --> 00:03:48.639 They compress the voice signal way down into a really 76 00:03:48.719 --> 00:03:51.599 narrow bandwidth that can ride on these low frequency carriers. 77 00:03:51.680 --> 00:03:54.560 Okay, compressing the data to fit the pipe essentially, So 78 00:03:54.639 --> 00:03:57.599 how is this TTE tech actually used? What are the 79 00:03:57.639 --> 00:03:59.080 applications for safety? 80 00:03:59.479 --> 00:04:02.840 Several really critical ones. There's an emergency broadcast network basically 81 00:04:02.879 --> 00:04:06.520 a way to send alerts out to everyone underground. 82 00:04:05.960 --> 00:04:07.759 Fast, like a mine white pager. 83 00:04:07.680 --> 00:04:11.479 Kind of Yeah. Then there's something called the GLNW transmitter. 84 00:04:11.560 --> 00:04:14.400 This is fascinating. It's a small transmitter built right into 85 00:04:14.400 --> 00:04:17.480 a miner's cap lamp, into the lamp itself, yep, and 86 00:04:17.519 --> 00:04:20.959 it acts as a locating transmitter. If there's a disaster, 87 00:04:21.399 --> 00:04:25.199 it helps rescuers pinpoint that person's exact location. It's even 88 00:04:25.199 --> 00:04:27.399 got a circuit breaker for the lamp. Bulp Why break 89 00:04:27.480 --> 00:04:30.800 the bulb circuit to save power. If the battery runs 90 00:04:30.879 --> 00:04:33.639 low and the bulb cuts out, the transmitter can still 91 00:04:33.720 --> 00:04:35.199 keep going for over seven. 92 00:04:35.000 --> 00:04:38.439 Days, seven days on its own battery after the light's 93 00:04:38.439 --> 00:04:39.639 dead seven days. 94 00:04:39.920 --> 00:04:42.480 It's an incredible safety margin for rescue ops. 95 00:04:42.560 --> 00:04:44.240 That's massive. What else uses. 96 00:04:44.040 --> 00:04:46.879 TTE, Well, there's a tram Guard minor track system. It's 97 00:04:47.000 --> 00:04:51.639 MSAHA approved a proximity warning for those big continuous mining machines. 98 00:04:51.759 --> 00:04:54.680 It logs data like who's near the machine and how far, 99 00:04:55.040 --> 00:04:57.600 and they're working on sending that data up via TTE. 100 00:04:57.920 --> 00:05:01.120 Real time proximity awareness important definitely. 101 00:05:01.560 --> 00:05:03.920 And then there's a mix of old and new minor signaling. 102 00:05:04.319 --> 00:05:06.360 If a miner is trapped, the traditional ways to pound 103 00:05:06.360 --> 00:05:07.759 on rock or pipes. 104 00:05:07.439 --> 00:05:08.439 Just bang on things. 105 00:05:08.680 --> 00:05:12.319 Yeah, but now there are surface arrays usually seven subrays 106 00:05:12.360 --> 00:05:15.399 of sensors that are listening for those specific pounding. 107 00:05:15.120 --> 00:05:18.399 Signals, high tech listening for low tech signals exactly. 108 00:05:18.519 --> 00:05:20.639 You need at least three of those subarrays to detect 109 00:05:20.639 --> 00:05:23.360 the signal to get a location fix, but five or 110 00:05:23.399 --> 00:05:25.079 more gives you much better accuracy. 111 00:05:25.199 --> 00:05:27.720 Wow. And there are dedicated devices too. 112 00:05:27.839 --> 00:05:30.680 Yes, like a system developed by CSR Mining tech in 113 00:05:30.720 --> 00:05:34.160 South Africa. It's a beltmorn tag with an LED and 114 00:05:34.199 --> 00:05:37.199 buzzer and it can locate a trapped miner through more 115 00:05:37.240 --> 00:05:38.519 than thirty meters of rock. 116 00:05:38.759 --> 00:05:42.079 Thirty meters is still a lot of rock to get through. Amazing. 117 00:05:42.839 --> 00:05:47.160 Now you mentioned specific frequencies for TTE. Was there a 118 00:05:47.240 --> 00:05:50.040 key moment, like a discovery of the perfect frequency? 119 00:05:50.160 --> 00:05:53.560 There? Absolutely was. This came out of lab experiments detailed 120 00:05:53.560 --> 00:05:56.600 in the source material. They tested tons of frequencies. Trying 121 00:05:56.600 --> 00:05:58.279 to send signals through coal strata. 122 00:05:58.480 --> 00:06:01.240 Must have been tricky, lots of absor or, like you said. 123 00:06:01.000 --> 00:06:03.879 Totally, but they found the sweet spot four hundred and 124 00:06:03.879 --> 00:06:08.839 fifty seven killohertz. That specific frequency gave the maximum signal 125 00:06:08.839 --> 00:06:09.639 strength through. 126 00:06:09.480 --> 00:06:12.600 Coal, four hundred and fifty seven killerhertz. Why was finding 127 00:06:12.680 --> 00:06:14.199 that one number such a big. 128 00:06:14.040 --> 00:06:17.199 Deal Because it wasn't just slightly better, It was significantly 129 00:06:17.199 --> 00:06:20.959 better for penetrating coal. Knowing this optimal frequency allowed engineers 130 00:06:21.000 --> 00:06:24.680 to design a detecting system for underground mind worker specifically 131 00:06:24.720 --> 00:06:25.319 tuned for it. 132 00:06:25.680 --> 00:06:28.120 Ah, So instead of just blasting out a signal and 133 00:06:28.160 --> 00:06:31.319 hoping they could focus the energy perfectly for that specific 134 00:06:31.439 --> 00:06:32.199 rock type. 135 00:06:32.079 --> 00:06:35.319 Exactly, it meant they could build systems often integrated right 136 00:06:35.360 --> 00:06:38.160 into the caplant batteries like that GOLO and w that 137 00:06:38.199 --> 00:06:41.879 were much more effective beacons, And crucially, they could make 138 00:06:41.920 --> 00:06:46.439 them intrinsically safe, limiting the power output to just two wants, 139 00:06:46.920 --> 00:06:49.079 yet still be confident the signal would get through. 140 00:06:49.360 --> 00:06:51.560 So four hundred and fifty seven Killer Herds wasn't just 141 00:06:51.600 --> 00:06:55.680 about range. It was about making reliable, safe rescue beacons possible. 142 00:06:55.720 --> 00:06:59.600 Precisely, it drastically cut down potential search times in a disaster. 143 00:07:00.240 --> 00:07:03.120 It changed rescue from maybe searching blind to having a 144 00:07:03.160 --> 00:07:06.199 target electronic signal to follow a huge leap. 145 00:07:06.319 --> 00:07:09.920 Incredible. Okay, so TTE is vital for emergencies and location. 146 00:07:10.639 --> 00:07:13.680 What about more general day to day wireless comms in 147 00:07:13.720 --> 00:07:16.079 the tunnels? What modern tech works down there? 148 00:07:16.240 --> 00:07:19.240 Yeah, for routine stuff, we see UHF transceivers quite a bit. 149 00:07:19.279 --> 00:07:21.879 They operate in the four and ten to five hundred megorheartz. 150 00:07:21.480 --> 00:07:23.879 Range, higher frequency than TTE right. 151 00:07:23.839 --> 00:07:26.600 And for safety, their power is strictly limited, usually just 152 00:07:26.639 --> 00:07:29.480 one or two wats radiated power. You find them in shafts, 153 00:07:29.519 --> 00:07:31.800 long wall mining areas, straight tunnels. 154 00:07:31.519 --> 00:07:34.319 Like specialized walkie talkies for mines pretty much. 155 00:07:34.360 --> 00:07:37.879 They work independently. They're lighter, don't use much power, and 156 00:07:38.000 --> 00:07:40.519 usually have about ten channels so multiple people can talk 157 00:07:41.160 --> 00:07:43.199 range wise. In a straight tunnel, you might get one 158 00:07:43.240 --> 00:07:45.519 hundred and seventy five two hundred meters at one watt, 159 00:07:45.800 --> 00:07:47.879 maybe up to three hundred meters at two watts. 160 00:07:48.160 --> 00:07:50.519 Okay, useful for line of sight or near line of sight, 161 00:07:50.920 --> 00:07:54.079 But minds twist and turn. How do you get signals 162 00:07:54.120 --> 00:07:54.920 around corners? 163 00:07:55.160 --> 00:07:58.720 Ah, that's where leaky feeder systems are brilliant. Imagine a 164 00:07:58.759 --> 00:08:01.000 special coaxial care strung. 165 00:08:00.680 --> 00:08:03.199 Through the tunnels like a regular antenna cable. 166 00:08:03.160 --> 00:08:05.639 Sort of, but this one is designed to deliberately leak 167 00:08:05.759 --> 00:08:09.120 radio signals out along its length and let signals leak 168 00:08:09.199 --> 00:08:09.480 back in. 169 00:08:09.920 --> 00:08:12.600 So the cable itself becomes the antenna path exactly. 170 00:08:12.639 --> 00:08:15.519 It grinds the radio waves usually VHF rounde hundred and 171 00:08:15.560 --> 00:08:17.959 forty six hundred and seventy four miker hertz around all 172 00:08:18.000 --> 00:08:19.000 the bends and corners. 173 00:08:19.079 --> 00:08:22.199 Clever does the signal weaken along the cable, It. 174 00:08:22.160 --> 00:08:25.000 Does, so they install line amplifiers every three hundred and 175 00:08:25.040 --> 00:08:27.839 fifty to five hundred meters to boost the signal back up. 176 00:08:28.120 --> 00:08:30.639 Sometimes they use passive amplifiers too, just to increase the 177 00:08:30.680 --> 00:08:33.559 signal strength radiating around the cable, maybe giving you up 178 00:08:33.559 --> 00:08:35.759 to fifty meters of wireless range near the feeder. 179 00:08:35.879 --> 00:08:39.039 A guided wave system makes sense. What about tech we 180 00:08:39.120 --> 00:08:42.200 use every day like Wi Fi? Does that actually work underground? 181 00:08:42.519 --> 00:08:46.399 It does surprisingly well in some setups. Wi Fi underground 182 00:08:46.440 --> 00:08:49.519 carries two way radio signals between access points and devices, 183 00:08:50.000 --> 00:08:53.320 often linked back to the service network, maybe even the Internet. 184 00:08:53.240 --> 00:08:56.519 So you could potentially use VoIP phones or send data. 185 00:08:56.559 --> 00:08:59.360 Absolutely it's digital, so you can run boys data, even 186 00:08:59.440 --> 00:09:03.360 video simultaneously. And we're seeing Wi Fi merging with leaky 187 00:09:03.360 --> 00:09:07.759 feeder concepts too. Some specialized mind phones actually combine standard 188 00:09:07.759 --> 00:09:10.799 cell signals with Wi Fi for better underground coverage. 189 00:09:11.039 --> 00:09:14.480 The familiar tech adapted. What about longer range wireless like. 190 00:09:14.519 --> 00:09:18.120 Wymax mymax has a role too. It's designed for longer distances, 191 00:09:18.159 --> 00:09:21.679 potentially covering up to fifty kilometers in handling maybe one thousand. 192 00:09:21.320 --> 00:09:22.799 Users fifty kilometers. 193 00:09:22.799 --> 00:09:26.080 That's huge range it is, and a key advantage for 194 00:09:26.159 --> 00:09:28.159 mining is its ability to work in non line of 195 00:09:28.200 --> 00:09:31.639 sight situations, which is a big problem for older wireless tech. 196 00:09:32.159 --> 00:09:34.879 Uses a technique called OFDM. 197 00:09:34.519 --> 00:09:39.000 Orthogonal frequency division multiplexing sounds complex? What's a simple version? 198 00:09:39.000 --> 00:09:40.080 Why is that good for minds? 199 00:09:40.200 --> 00:09:42.559 Okay? Think of it like this. You're in a really 200 00:09:42.639 --> 00:09:46.360 echoby tunnel. If you shout, the echoes bounce all over 201 00:09:46.519 --> 00:09:47.960 and make it hard to understand. 202 00:09:48.120 --> 00:09:48.279 Right. 203 00:09:48.360 --> 00:09:53.080 Multipath interference exactly OFDM takes the signal, say, your voice data, 204 00:09:53.559 --> 00:09:56.440 and splits it into lots and lots of tiny pieces. 205 00:09:57.080 --> 00:10:01.799 Each piece gets sent on its own, separate, very narrow 206 00:10:01.799 --> 00:10:05.080 frequency channel. Okay, So even if some of those little 207 00:10:05.080 --> 00:10:07.759 signals get messed up by echoes bouncing off the walls, 208 00:10:08.000 --> 00:10:10.279 most of go through cleanly because they're on different frequencies 209 00:10:10.320 --> 00:10:12.840 and don't interfere with each other as much. The receiver 210 00:10:12.960 --> 00:10:15.960 can piece the original message back together. It's really resilient 211 00:10:16.000 --> 00:10:17.159 to that echoee environment. 212 00:10:17.480 --> 00:10:20.279 Ah, So it fights the echoes by splitting the signal up. 213 00:10:20.639 --> 00:10:23.080 Very smart. And I guess Bluetooth fits in somewhere for 214 00:10:23.120 --> 00:10:24.159 short range stuff. 215 00:10:24.279 --> 00:10:26.960 Yeap, Bluetooth is there too, Yeah, just the standard short 216 00:10:27.000 --> 00:10:30.840 range wireless good for connecting headsets, maybe transferring small bits 217 00:10:30.840 --> 00:10:34.679 of data locally between devices useful, but not for general 218 00:10:34.720 --> 00:10:35.519 mind communication. 219 00:10:35.919 --> 00:10:40.360 Got it? Okay? Beyond just talking modern mind safety really 220 00:10:40.440 --> 00:10:43.320 relies on knowing where everyone and everything is and what 221 00:10:43.399 --> 00:10:46.480 the environment is like gas levels, temperature, et cetera. That 222 00:10:46.600 --> 00:10:49.559 sounds like sensor networks and RFID territory. 223 00:10:49.679 --> 00:10:53.279 Absolutely, this is where things get really interconnected. Zigbie technology 224 00:10:53.320 --> 00:10:55.639 is a major player here. It's based on the IEE 225 00:10:55.799 --> 00:10:58.720 eight to two point one five point four standard, designed 226 00:10:58.720 --> 00:11:03.000 for simple, low cost and crucially very low power wireless networks. 227 00:11:03.120 --> 00:11:06.519 Low power is key underground right, Changing batteries must be a. 228 00:11:06.480 --> 00:11:09.559 Pain, a huge pain. With Zigbie, we're talking about sensors 229 00:11:09.639 --> 00:11:13.679 running on batteries that can last for years, years. Seriously, seriously, 230 00:11:13.840 --> 00:11:16.600 that's a game changer for maintenance. Zigbi is ideal for 231 00:11:16.679 --> 00:11:20.399 deploying huge numbers of sensors that gas monitors, temperature sensors, 232 00:11:20.639 --> 00:11:23.399 maybe even stress monitors in the rock and control devices. 233 00:11:23.679 --> 00:11:25.320 It handles lots of nodes really well. 234 00:11:25.399 --> 00:11:26.639 What frequencies does it use? 235 00:11:26.759 --> 00:11:29.480 It uses a few bands, including the eighty six, one hundred, 236 00:11:29.559 --> 00:11:32.320 nine hundred and fifteen megahertz spans in some regions and 237 00:11:32.360 --> 00:11:35.639 the worldwide two point four gigahertz ism ban which is 238 00:11:35.639 --> 00:11:38.039 the same as Wi Fi and Bluetooth and has really 239 00:11:38.039 --> 00:11:39.720 good receiver sensitivity like. 240 00:11:39.679 --> 00:11:42.559 That neck at eighty five dBm number mentioned in the source. 241 00:11:42.600 --> 00:11:43.799 What does that sensitivity mean? 242 00:11:43.840 --> 00:11:46.720 Practically right, that nake out to VD five at dam figure. 243 00:11:47.000 --> 00:11:50.279 It means the Zigbi receivers can pick up incredibly weak signals. 244 00:11:50.840 --> 00:11:53.759 In a mind where signals fade fast through rock or 245 00:11:53.840 --> 00:11:57.720 down long tunnels, being able to reliably hear feint transmissions 246 00:11:57.720 --> 00:12:01.559 from distant or low power sensors is absolutely critical. It 247 00:12:01.600 --> 00:12:03.039 means your network coverage. 248 00:12:02.720 --> 00:12:05.720 Is much more robust, so it ensures data gets through 249 00:12:05.799 --> 00:12:08.679 even when the signal is barely there. Makes sense. What 250 00:12:08.720 --> 00:12:10.519 are the other pluses of Zigby. 251 00:12:10.440 --> 00:12:13.600 Well, it's relatively low cost. Installation and maintenance are simpler, 252 00:12:13.679 --> 00:12:16.639 and the networks can often configure themselves, which reduces set 253 00:12:16.720 --> 00:12:17.159 up hassle. 254 00:12:17.240 --> 00:12:20.200 All right, so Zigby builds the network. What about identifying 255 00:12:20.240 --> 00:12:24.240 things on that network, like people and equipment. That's RFID, Yeah, exactly. 256 00:12:24.360 --> 00:12:27.879 RFIDA radio frequency identification. It's a way to collect data 257 00:12:28.000 --> 00:12:31.360 using electronic tags attached to objects or people, and wireless 258 00:12:31.360 --> 00:12:33.679 readers pick up the tags ID using radio waves. 259 00:12:34.000 --> 00:12:36.399 We see it in stores for logistics. How does it 260 00:12:36.440 --> 00:12:38.759 work in minds? Are there different types of tags? 261 00:12:39.039 --> 00:12:43.200 Yes? Three main types Passive tags are the simplest, no battery. 262 00:12:43.360 --> 00:12:45.639 They get powered up briefly by the reader's signal when 263 00:12:45.679 --> 00:12:48.879 they get close. Range is short maybe centimeters up to 264 00:12:48.919 --> 00:12:52.799 potentially one hundred and eighty meters with very specialized reader arrays. 265 00:12:53.080 --> 00:12:55.120 Okay, cheap and simple but short range. 266 00:12:55.279 --> 00:12:58.159 Right. Then you have active tags. These have their own 267 00:12:58.240 --> 00:13:01.039 battery That makes them much more liable and tough RF 268 00:13:01.120 --> 00:13:04.679 environments like mines, and gives them ranges of hundreds of meters. 269 00:13:04.679 --> 00:13:06.639 Battery life could be up to ten years. 270 00:13:06.360 --> 00:13:08.039 Ten years, and they can do more. 271 00:13:08.200 --> 00:13:12.559 Yes, active tags can incorporate other sensors temperature, humidity, maybe motion. 272 00:13:12.879 --> 00:13:14.600 They're like little data logging beacons. 273 00:13:14.679 --> 00:13:17.679 Okay, active tags are powerful. What's the third type? 274 00:13:17.960 --> 00:13:20.519 Semi passive? They have a battery, but only to power 275 00:13:20.519 --> 00:13:24.039 the microchip inside. They still use the reader's signal to 276 00:13:24.080 --> 00:13:27.559 send their ID back a technique called backscattering. This gives 277 00:13:27.559 --> 00:13:30.879 them better sensitivity than passive tags and longer life than 278 00:13:30.879 --> 00:13:33.840 if they are constantly transmitting like active tags. And some 279 00:13:33.960 --> 00:13:36.960 tags are incredibly tiny, like the Tachi chip point zher 280 00:13:37.000 --> 00:13:39.559 five by point zero five millimeters. 281 00:13:39.080 --> 00:13:42.039 Practically invisible. So how are all these tags used for 282 00:13:42.159 --> 00:13:43.600 safety and efficiency down there. 283 00:13:43.759 --> 00:13:47.360 Oh, In many ways, tracking helps respond faster if equipment 284 00:13:47.399 --> 00:13:50.639 goes down. You know exactly who is entering or leaving 285 00:13:50.679 --> 00:13:54.799 certain zones. You can control access to hazardous areas, automatically 286 00:13:54.879 --> 00:13:58.879 warn people yes, worn miners if they're approaching danger, track vehicles, 287 00:13:59.240 --> 00:14:03.639 track inventory. It really improves situational awareness. And this all 288 00:14:03.679 --> 00:14:06.679 comes together in systems like WIS the Wireless Information and 289 00:14:06.720 --> 00:14:08.399 Safety System YSS. 290 00:14:08.399 --> 00:14:09.320 What does that involve? 291 00:14:09.600 --> 00:14:13.919 YSS integrates all these RFID components, coordinators managing the network, 292 00:14:14.000 --> 00:14:17.039 routers extending the range, and the end devices, the tags 293 00:14:17.080 --> 00:14:19.559 worn by minors or put on equipment. They form a 294 00:14:19.639 --> 00:14:21.559 dynamic wireless mesh network. 295 00:14:21.919 --> 00:14:24.240 Mesh network means the devices talk to each other to 296 00:14:24.279 --> 00:14:26.039 pass signals along exactly. 297 00:14:26.080 --> 00:14:29.600 It makes the network very resilient. So ISSS allows real 298 00:14:29.639 --> 00:14:33.240 time tracking of everyone and key equipment. It can monitor 299 00:14:33.279 --> 00:14:35.759 for unsafe practices like maybe someone going too fast in 300 00:14:35.799 --> 00:14:39.039 a vehicle. It gives audio visual warnings directly to miners 301 00:14:39.159 --> 00:14:40.240 entering restricted. 302 00:14:39.919 --> 00:14:41.919 Zones, warning's right on the person, yes. 303 00:14:42.559 --> 00:14:47.360 And it constantly monitors the environment methane, carbon monoxide, air speed, temperature, 304 00:14:47.799 --> 00:14:51.159 even small movements in the rock strata. It can even 305 00:14:51.240 --> 00:14:54.360 send coded text messages from underground up to the surface 306 00:14:54.360 --> 00:14:54.960 control room. 307 00:14:55.159 --> 00:14:58.320 Wow, that's comprehensive. Is there software to manage all this data? 308 00:14:58.480 --> 00:15:02.000 Yeah? Typically tracking and MI on entering software TMS. It 309 00:15:02.039 --> 00:15:05.399 gives surface control a graphical display MAPPS showing where everyone is, 310 00:15:05.480 --> 00:15:09.159 their paths, attendance records, It generates safety reports. It's like 311 00:15:09.200 --> 00:15:13.039 having a real time digital twin of the underground operation. 312 00:15:12.799 --> 00:15:17.039 And incredible safety net. Now beyond these big network systems, 313 00:15:17.080 --> 00:15:20.840 are there any really specialized, almost niche tools developed just 314 00:15:20.879 --> 00:15:23.360 for rescue or unique communication needs. 315 00:15:23.639 --> 00:15:26.600 There are some fascinating ones. Take the tooth microphone. 316 00:15:26.240 --> 00:15:28.000 A tooth microphone, Yeah, you heard right. 317 00:15:28.120 --> 00:15:31.080 It's a dental bone conduction system. You clip a tiny 318 00:15:31.120 --> 00:15:33.759 device to your upper molars. It picks up your voice 319 00:15:33.840 --> 00:15:35.240 vibrations through the bone. 320 00:15:35.000 --> 00:15:36.840 So you talk through your teeth essentially. 321 00:15:36.960 --> 00:15:40.639 Yes, it connects wirelessly to a transceiver. The beauty is 322 00:15:40.799 --> 00:15:45.799 it gives incredibly clear voice transmission even in extremely noisy environments. 323 00:15:46.080 --> 00:15:48.200 And it works perfectly even if you're wearing a full 324 00:15:48.200 --> 00:15:51.600 breathing apparatus mask that would normally muffle your voice. 325 00:15:51.679 --> 00:15:55.120 That's brilliant for rescue teams working in smoke or gas. 326 00:15:55.039 --> 00:15:57.600 Exactly ideal for first responders. 327 00:15:57.679 --> 00:15:59.039 What else is out there for rescue? 328 00:15:59.159 --> 00:16:03.399 There's the super Low frequency or SLF beacon. This is 329 00:16:03.399 --> 00:16:06.080 a device that trapped miner can activate. It sends out 330 00:16:06.240 --> 00:16:08.799 very low frequency pulses like twenty to two hundred hertz, 331 00:16:09.080 --> 00:16:10.600 about one pulse per second. 332 00:16:10.559 --> 00:16:12.600 Even lower frequency than TTE. 333 00:16:12.519 --> 00:16:15.759 Much lower. It transmits these pulses through a big, detactable 334 00:16:15.799 --> 00:16:19.039 loop antenna basically a long cable maybe sixteen to thirty 335 00:16:19.039 --> 00:16:21.879 three meters that the miner deploys, and the whole thing 336 00:16:21.919 --> 00:16:23.840 is designed to be completely explosion proof. 337 00:16:24.080 --> 00:16:27.320 Okay, so the minor activates it, how do rescuers find it? 338 00:16:27.600 --> 00:16:31.080 They use portable SLF receivers on the surface. These receivers 339 00:16:31.080 --> 00:16:34.279 are tuned to those specific low frequencies. By monitoring the 340 00:16:34.320 --> 00:16:36.840 signal strength as they move around, they can hole me 341 00:16:36.879 --> 00:16:39.120 in on the beacon's location and find the trapped miner. 342 00:16:39.559 --> 00:16:42.159 It's a very direct location method when other comms might 343 00:16:42.200 --> 00:16:43.080 be totally out. 344 00:16:43.120 --> 00:16:47.600 A lifeline signal. What about the shafts. Communicating up and 345 00:16:47.639 --> 00:16:50.240 down one thousand foot shaft while moving in a cage 346 00:16:50.279 --> 00:16:51.720 seems like a unique problem. 347 00:16:51.879 --> 00:16:54.559 It really is. For that, they often use an induction 348 00:16:54.679 --> 00:16:58.360 based hoist communication system. This is neat. It uses the 349 00:16:58.360 --> 00:17:01.480 actual steel hoist ropes and eyed ropes in the shaft 350 00:17:01.559 --> 00:17:02.960 as part of the communication circuit. 351 00:17:03.080 --> 00:17:04.880 The ropes themselves carry the signal. 352 00:17:05.279 --> 00:17:09.079 How it uses low frequency electromagnetic waves maybe around thirty 353 00:17:09.079 --> 00:17:12.400 two kilohertz. Special ferret couplers clap around the ropes to 354 00:17:12.440 --> 00:17:15.480 transmit and receive these signals. It works on the principle 355 00:17:15.480 --> 00:17:19.480 of magnetic coupling. Changing electrical currents in the system induce 356 00:17:19.559 --> 00:17:22.480 magnetic fields around the ropes, and those fields carry the 357 00:17:22.519 --> 00:17:24.640 signal up and down the shaft. 358 00:17:24.759 --> 00:17:27.559 So the cage, the pit, bottom, the surface they can 359 00:17:27.599 --> 00:17:28.400 all talk clearly. 360 00:17:28.559 --> 00:17:31.720 Yes, continuous voice communication for people in the moving cage, 361 00:17:31.759 --> 00:17:34.799 people at the top, people at the bottom, absolutely vital 362 00:17:34.880 --> 00:17:38.640 for maintenance checks, coordinating movements, and of course emergencies in 363 00:17:38.680 --> 00:17:39.119 the shaft. 364 00:17:39.519 --> 00:17:42.759 Applying basic physics principles in a really smart way. 365 00:17:43.960 --> 00:17:47.480 Okay, all this tech is incredible solving massive challenges. But 366 00:17:47.559 --> 00:17:52.519 you mentioned minds often have explosive atmospheres methane gas, cold dust. 367 00:17:53.039 --> 00:17:56.279 How do you ensure none of this electrical equipment causes 368 00:17:56.319 --> 00:17:59.000 a spark or gets hot enough to cause an explosion. 369 00:17:59.559 --> 00:18:01.839 There must be an ultimate safety layer. 370 00:18:02.240 --> 00:18:05.440 You've hit on the absolute bedrock of mind safety engineering, 371 00:18:05.920 --> 00:18:09.960 Intrinsic safety or is. It's not just a feature, it's 372 00:18:10.000 --> 00:18:13.640 a fundamental design philosophy. It's considered the highest level of 373 00:18:13.680 --> 00:18:17.000 protection for electrical gear and potentially explosive. 374 00:18:16.480 --> 00:18:18.759 Places, higher than just putting it in a strong box. 375 00:18:18.920 --> 00:18:22.680 Much higher explosion proof enclosures contain an explosion if it 376 00:18:22.720 --> 00:18:26.400 happens inside. Intrinsic safety aims to prevent the ignition from 377 00:18:26.440 --> 00:18:27.759 ever happening in the first place. 378 00:18:28.000 --> 00:18:29.359 Oh, how do you guarantee that? 379 00:18:29.480 --> 00:18:33.200 By rigorously limiting the electrical energy, voltage, current, and total 380 00:18:33.240 --> 00:18:36.279 power available in the circuits to levels that are physically 381 00:18:36.279 --> 00:18:39.400 incapable of creating a spark hot enough or a surface 382 00:18:39.440 --> 00:18:42.240 hot enough to ignite the surrounding atmosphere even if something 383 00:18:42.279 --> 00:18:44.559 goes wrong like a short circuit or component failure. 384 00:18:44.599 --> 00:18:47.279 So it's designed to be safe even when it fails exactly. 385 00:18:47.319 --> 00:18:51.119 It's an incredible engineering discipline. Think about the details the 386 00:18:51.200 --> 00:18:54.680 printed circuit board, the PCB itself. There are strict rules 387 00:18:54.720 --> 00:18:57.640 for its minimal thickness, how wide the copper tracks can be, 388 00:18:58.160 --> 00:19:01.279 and it needs a specific temperature classification like T four 389 00:19:01.359 --> 00:19:01.839 for Group I. 390 00:19:01.960 --> 00:19:04.640 Minds T four group II. What do those mean? In practice? 391 00:19:04.839 --> 00:19:08.039 T four means the maximum temperature any surface on that 392 00:19:08.079 --> 00:19:11.240 device can reach underfall conditions is one hundred and thirty 393 00:19:11.240 --> 00:19:14.319 five degrees celsius, well below the ignition temperature of methane. 394 00:19:14.480 --> 00:19:17.599 Group I specifically refers to the mining environment with methane 395 00:19:17.839 --> 00:19:20.680 and coal dust hazards. So T four group I means 396 00:19:20.720 --> 00:19:23.359 it's safe for those specific dangerous conditions. 397 00:19:23.559 --> 00:19:25.240 Every component is rated, every. 398 00:19:25.079 --> 00:19:28.799 Single one, even tiny resistors are capacitors. If a component 399 00:19:28.839 --> 00:19:31.400 could get hotter than the limit, it needs special protection 400 00:19:31.720 --> 00:19:36.160 or design considerations. Reactive components like inductors, coils, and capacitors 401 00:19:36.359 --> 00:19:37.480